Apparatus for cooling air-conditioning refrigerant

ABSTRACT

An apparatus for treating refrigerant which passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature circulating in a transcritical air conditioning loop having a heat exchanger with a collecting tube. A longitudinal vessel is connected to the heat exchanger collecting tube and defines a heat exchanger chamber and an accumulator chamber, wherein both of the chambers extend parallel over at least a significant portion of the length of the vessel. The vessel includes at least one longitudinal wall having an opening allowing the refrigerant to flow through the chambers. A flat multi-chamber tube extends through the heat exchanger chamber of the vessel, wherein refrigerant on one side flows through the tube and refrigerant on the other side flows through the vessel to exchange heat between refrigerant in the sides.

CROSS REFERENCE TO RELATED APPLICATION(S)

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

TECHNICAL FIELD

The present invention relates to heat exchangers, and more particularly toward intermediate cooling of refrigerant circulating in an air-conditioning loop.

BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART

Air-conditioning loops commonly include a refrigerant flowing through a compressor, gas cooler, evaporator (heat exchanger) and expansion valve, where the refrigerant passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature.

One heat exchanger for exchanging heat between the high and low pressure sides, often referred to as an internal heat exchanger in transcritical air conditioning loops, is known from DE 196 35 454 A1 which provides improved heat exchange rates. However, manufacture of this device (arranged flat in the incorporation space in the vehicle) appears to be fairly demanding, among other things because the flat multi-chamber tubes are deformed as coils and insertion of the heat-conducting ribs between the windings of the coils is also complicated.

An intermediate heat exchanger is also disclosed in DE 103 22 028 B4, which is integrated as a coaxial tube in the collecting tube of the evaporator. This is a compact configuration which provides some ease of manufacture.

Another device for the same area of application is disclosed in U.S. Pat. No. 6,681,597 B1, in which the high pressure side and low pressure side flow through extruded, flat multi-chamber tubes which extend into a collection reservoir with their broad flat sides in conductive heat exchange relationship.

In another prior art configuration, German Patent DE 199 18 617 C2 discloses an accumulator and an separate internal heat exchanger combined with the gas cooler to provide a compact configuration. In that structure, the accumulator is connected to a collecting tube of the gas cooler, and the internal heat exchanger is situated on the upper or lower edge of the gas cooler (i.e., parallel to its tubes). The structure is right in the area of influence of the cooling air, which in summer has a temperature of about 30° C. to 40° C., and therefore tends to counteract the intended effect of the internal heat exchanger, with the degree of intended cooling of the refrigerant on the high pressure side being reduced somewhat by the relatively high temperature of the cooling air. Further, the internal heat exchanger would be costly to produce, and its connection to the gas cooler also appears to be difficult to execute in terms of design.

The present invention is directed toward improving upon the prior art to provide an easy to manufacture, compact heat exchanger for high and low pressure sides of an air-conditioning loop which provides efficient heat exchange.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an apparatus is provided for treating refrigerant which passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature circulating in a transcritical air conditioning loop. The loop includes a heat exchanger with a collecting tube. A longitudinal vessel is connected to the heat exchanger collecting tube and defines a heat exchanger chamber and an accumulator chamber, wherein both of the chambers extend parallel over at least a significant portion of the length of the vessel. A flat multi-chamber tube extends through the heat exchanger chamber of the vessel, wherein refrigerant on one side flows through the tube and refrigerant on the other side flows through the vessel.

In one form of this aspect of the present invention, an introduction tube is provided for the low pressure side in the accumulator chamber. In a further form, a dryer is associated with the introduction tube.

In another form of this aspect of the present invention, the vessel includes at least one longitudinal wall, wherein one end includes at least one inflow opening for the low pressure side from the vessel accumulator chamber into the vessel heat exchanger chamber. In a further form, at least one opening is on the other end of longitudinal wall for oil contained in the refrigerant. In another further form, the longitudinal wall is spaced from the center plane of the vessel whereby the accumulator chamber is larger than the heat exchanger chamber.

In still another form of this aspect of the present invention, the heat exchanger chamber extends over a partial radius of the vessel interior.

In yet another form of this aspect of the present invention, the vessel and the flat multi-chamber tube are extruded. In a further form, the multi-chamber tube extends substantially undeformed through the heat exchanger chamber of the vessel and heat conducting ribs are in the remaining cross-section of the heat exchanger chamber over a majority of the length of the heat exchanger chamber.

In another form of this aspect of the present invention, the vessel is an extruded tube having ends closed by a cover. In a further form, the extruded tube includes a longitudinal wall separating the heat exchanger chamber from the accumulator chamber. In an alternative further form, an insulation plate is in the tube and, in a further form, grooves are molded on opposite sides of the tube wall with the insulation plate is inserted in the grooves.

In still another form of this aspect of the present invention, an insulation plate is adjacent the longitudinal wall.

In yet another form of this aspect of the present invention, shielding is between the vessel and the cooling air stream flowing through the heat exchanger. In a further form, the heat exchanger is a gas cooler.

In a further form of this aspect of the present invention, the collecting tube of the heat exchanger and the vessel are assembled compactly together.

In a still further form of this aspect of the present invention, a vessel is behind an air baffle in the air flow direction.

In yet another form of this aspect of the present invention, insulation is at least partially on the outside of the vessel.

In a further form of this aspect of the present invention, one or more refrigerant treating filters is in the vessel.

In another aspect of the present invention, an apparatus is provided for treating refrigerant which passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature circulating in a transcritical air conditioning loop. A slim, hollow longitudinal vessel has at least one longitudinal wall and defines a heat exchanger chamber and an accumulator chamber. Both of the chambers extend parallel over at least a significant portion of the length of the vessel and the vessel includes at least one longitudinal wall having an opening allowing the refrigerant to flow through the chambers. A flat multi-chamber tube extends through the heat exchanger chamber of the vessel, wherein refrigerant on one side flows through the tube and refrigerant on the other side flows through the vessel to exchange heat between refrigerant in the sides.

In one form of this aspect of the present invention, the flat multi-chamber tube extends lengthwise through the heat exchanger chamber with heat conducting ribs. In a further form, the multi-chamber tube and the heat conducting ribs are extruded.

In another form of this aspect of the present invention, the inserted longitudinal wall has a lower heat transfer value than the walls of the vessel. In a further form, the inserted longitudinal wall consists of plastic.

In still another form of this aspect of the present invention, heat conducting ribs are in the remaining cross-section of the heat exchanger chamber outside of the multi-chamber tube.

In yet another form of this aspect of the present invention, the longitudinal wall is spaced from the center plane of the vessel.

In still another form of this aspect of the present invention, a dryer is in the accumulator chamber and a filter is in the vessel.

In another form of this aspect of the present invention, the vessel has a length (L) and a diameter (D), and the ratio of length (L) to diameter (D) is ≧3:1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-section through am apparatus according to the present invention;

FIG. 2 is a transverse cross-section along line 2-2 of FIGS. 1 and 3;

FIG. 3 is a longitudinal cross-section through a second embodiment of the apparatus according to the present invention;

FIG. 4 is a transverse cross-section through a vessel according to one embodiment of the present invention;

FIG. 5 is an end view of an alternate design to the multi-chamber tube illustrated in FIG. 4;

FIG. 6 is a transverse cross-section through an alternate vessel incorporating aspects of the present invention;

FIG. 7 is a transverse cross-section through another alternate vessel incorporating aspects of the present invention;

FIG. 8 is a transverse cross-section through still another alternate vessel incorporating aspects of the present invention;

FIGS. 9-12 schematically illustrate the connection of the apparatus to a gas cooler, wherein:

-   -   FIG. 9 is a front schematic view;     -   FIG. 10 is a cut-out schematic top view of the apparatus;     -   FIG. 11 is a transverse cross-section through yet another         alternate vessel; and     -   FIG. 12 is a partial front schematic view showing an alternate         connection of the gas cooler to the apparatus.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated, for example, in FIG. 1, the present invention includes, inter alia, a longitudinal, relatively slim, vessel 20 produced by extrusion with a longitudinal wall 30 defining an accumulator chamber 24 and a heat exchanger chamber 28. The longitudinal wall 30 divides the vessel 20 into the two mentioned chambers 24, 28, which extend parallel and essentially over the entire length of vessel 20. A dryer 34, which in the illustrated practical examples is outside of an introduction tube 36, is situated in the accumulator chamber 24.

A flat multi-chamber tube 38 extends through the heat exchanger chamber 28. The tube 38 may advantageously be extruded and extruded to extend essentially straight over at least a significant length of the vessel 20 so that, among other things, relatively cost-effective production of the apparatus is attained. A heat-conducting rib 39 may advantageously extend around the entire periphery of the multi-chamber tube, which rib 39 also essentially fills up the remaining cross-section of the heat exchanger chamber 28 in order to be able to obtain good results with respect to heat exchange efficiency.

Insulation 40 may advantageously cover the surface of the vessel 20, particularly wherever it is advantageous to avoid temperature effects from the environment on heat exchange in vessel 20 (e.g., where there are unduly high outside temperatures).

The cooler refrigerant on the low pressure side flows through an opening 42 in the upper cover 46 into collector chamber 24. To support the accumulator function or depositing of liquid and oil, the introduction tube 36 extends into the accumulator chamber 24.

Variations of the apparatus according to the present invention for treatment of the refrigerant are shown in FIGS. 1 and 3. These variations differ in their arrangement of the filter 50 and the accumulator chamber 24 and in the heat exchanger chamber 28.

In the FIG. 1 variation, this refrigerant flows through a filter 50 on the end of the introduction tube 36. Oil and residual liquid refrigerant present in the refrigerant are deposited in the accumulator chamber 24 on the bottom. The gaseous refrigerant on the top flows through an inflow opening 52 in the longitudinal wall 30 into heat exchanger chamber 28 and flows downward through heat conducting ribs 39 to reach the outlet 58 arranged in the wall of the vessel 20. The warmer refrigerant on the high pressure side flows via a channel 60 in the upper cover 46 into the multi-chamber tube 38, and flows downward in the multi-chamber tube 38, in order to leave the vessel 20 toward an expansion device (not shown) and the evaporator via the outlet channel 70 in the lower cover 46 (after heat release to the refrigerant on the low pressure side and in a further cooled state that therefore improves performance). (The described flow direction merely serves for the understanding of the figures).

A channel 72 and a hole 74 beneath the longitudinal wall 30 feed oil deposited in the accumulator 24 to the refrigerant on the low pressure side after passing through heat exchanger chamber 28 (FIG. 2).

In the practical example according to FIG. 3 two flat filter elements 78 are provided, with one in front of channel 72 and the second is situated in front of the already-mentioned outlet 58 in the heat exchanger chamber 28. It should be appreciated that this embodiment offers greater configuration latitude for the designer in terms of positioning such elements.

FIG. 4 shows the cross-section through the vessel 20 of another advantageous variation of the present invention whereby a larger or specially configured accumulator chamber 24 may be provided where required. As illustrated, the flat multi-chamber tube 38 is manufactured with a shape adapted to the contour of vessel 20 so that the tube 38 may extend along part of the vessel wall. Receiving grooves 80, into which the longitudinal edges of a longitudinal wall 30 can be pushed, are situated on the inside of the vessel wall. The receiving grooves 80 can readily be produced by extrusion along with the rest of the vessel 20.

The multi-chamber tube 38 may also advantageously be an extruded tube with, for example, two rows of passages 84. This design is particularly preferred if, as shown in FIG. 5, the corrugated heat exchange ribs 39 are to be dispensed with as a separate part, equipping the multi-chamber tube 38 on the outside with rib-like channels. It is also possible here, according to a modification not shown, to design the longitudinal wall 30 as one piece with the multi-chamber tube 38 so that the longitudinal wall 30 mounted in the receiving grooves 80 can be dispensed with. In this case all parts consist of metal, for example aluminum. However, certain already-mentioned advantages are obtained for heat exchange if the longitudinal wall 30 is produced from a material with low heat conductivity, for example plastic. That is, undesired heat transfer between the accumulator chamber 24 and the heat exchanger chamber 28 is suppressed. Therefore, heat exchange will essentially occur in the heat exchanger chamber 24 which is specially equipped for this purpose. Overall this leads to somewhat higher temperature differences between the low pressure side and the high pressure side in the heat exchanger chamber 28 itself, from which improved efficiency of heat exchange results.

FIGS. 6-8 show additional practical examples in cross-section through an extruded vessel 20 with two longitudinal walls 30, forming three chambers or compartments in the vessel 20. It should be appreciated that the chambers 24, 28 can be designed according to the desired application as accumulator.

In the example according to FIG. 6, the middle chamber is the heat exchanger chamber 28 and the two other chambers are accumulator chambers 24. A multi-chamber tube 38 is situated in the heat exchanger chamber 28, such was already described above with reference to FIG. 5.

In the FIG. 7 example, the middle chamber is the accumulator chamber 24 and the other chambers are the heat exchanger chambers 28, wherein the wall thickness of the vessel 20 is partially increased at 88 to provide a chamber cross-section (while retaining the round cross-sectional shape of vessel 20) which facilitates the introduction of the tube 38 and heat exchanger rib 39. Ordinary corrugated ribs 39 can then be used which are wound in coiled fashion around tube 38. In other cases this “equalized” cross-section may also be advantageously used with the accumulator chamber 24. An equalized cross-section is achieved in the FIG. 8 example by a slight deviation from the round vessel shape, which is still tolerable despite the high pressures in the system. That is, as is apparent from FIG. 8, four gradations 90 are spaced about the periphery of vessel 20, which allows the cross-section of the upper and lower heat exchanger chambers 28 to be roughly rectangular (with the middle chamber in the FIG. 8 embodiment being an accumulator chamber 24).

The above described apparatus may be advantageously used for treatment of a refrigerant circulating in an air-conditioning loop containing, for example, a compressor, a gas cooler, an evaporator (heat exchanger) and an expansion device, where the refrigerant passes through a high pressure side and a low pressure side in which the refrigerant has different temperature. Refrigerant on one side flows through the tube 38 and on the other side flows through the heat exchanger chamber 28 outside the tube 38 in order to serve as an intermediate heat exchanger, with the accumulator chamber 24 formed in the vessel 20 with the heat exchanger chamber 28. For example, it should be appreciated that the apparatuses described in the practical examples may be advantageously used in air conditioning units of vehicles in a roughly upright arrangement.

For example, the apparatus is shown in such a system in FIGS. 9-12 combined with a gas cooler 92 in order to achieve a particularly compact configuration of the entire system, where the vessel 20 is, in principle, like the one shown in FIG. 3 and already described above.

As is common in air conditioning units with a two-phase refrigerant from the prior art, the vessel 20 is arranged and therefore connected in parallel to a collecting tube. In the present invention, however, the vessel 20 is connected to the gas cooler 92 and, whereas only a collector was involved in the prior art, with the FIGS. 9-12 aspect of the present invention an accumulator (accumulator chamber 24) is compactly combined with an inner heat exchanger 28 which is connected to a gas cooler 92. Specifically, in the depicted practical example, the vessel 20 is fastened by means of two holders 94 to a collecting tube 96 of the gas cooler 92.

The necessary components of the air conditioning loop on the inflow and outflow sites for the refrigerant on the low pressure side (LP) and high pressure side (HP) are indicated in FIG. 9 by corresponding inscription. The gas cooler 92 receives compressed, gaseous high pressure refrigerant at high temperature coming from the compressor, which is cooled in the gas cooler 92 by heat exchange with the cooling air. The coil-like flow through the gas cooler 92 through groups of parallel flat tubes is indicated by arrows. Partitions may be provided in the collecting tubes 96 of the gas cooler 92 to cause the described flow. The high pressure refrigerant in the practical example enters the heat exchanger chamber 28 directly after leaving the gas cooler 92 and, as described, enters the multi-chamber tube 38 extending through chamber 28.

As illustrated in FIG. 9, high pressure refrigerant flows from the gas cooler 92 to the vessel 20 by means of a short line 98 from the collecting tube 96 into the multi-chamber tube 38. A somewhat more compact alternative design is shown in FIG. 12, wherein the line 98 passes through a holder 94 and is connected on multi-chamber tube 38.

The low pressure refrigerant comes from the evaporator in a supercooled state, and enters the accumulator chamber 24 through the introduction tube 36 extending into the accumulator chamber 24, with the low pressure refrigerant passing through the dryer 34 and a filter 50 at the end of the introduction tube 36. In contrast to the previously described alternatives, the opening for the oil is situated in the longitudinal wall 30 directly in the area of the bottom. The inflow opening 52 for the gaseous low pressure refrigerant is at the upper end of the longitudinal wall 30, whereby the low pressure refrigerant flows through the heat exchanger ribs 39 in the heat exchanger chamber 28 and then out from the bottom of the chamber 28 in the direction toward the compressor (not shown). The refrigerant is then enriched with oil and deposited liquid refrigerant which, because of the heat taken up in the heat exchanger, is immediately converted to the gaseous state and assumes a lower temperature so that the compressor is unloaded.

FIG. 11 shows a modified embodiment in which the vessel 20 produced by extrusion has no integrated longitudinal wall 30 but is instead merely equipped with receiving grooves 80. These receiving grooves 80 allow a plastic longitudinal wall 30A to be readily inserted into the vessel 20, thereby offering advantages with respect to efficiency of heat exchange and can be executed despite the prevailing high pressure because no noticeable pressure difference is present between the heat exchanger chamber 28 and the accumulator chamber 24.

An additional plastic longitudinal wall may also be added directly to the metal longitudinal wall 30, as illustrated by the two parallel lines in FIGS. 9 and 10.

Further, it should be appreciated that the vessel 20 of the proposed apparatus is advantageously characterized by a slim configuration. The ratio of its length L to its diameter D (see FIG. 3) is at least 3:1, with the ratio preferably being about 6:1.

Thus, it should be appreciated that a particularly compact and effective apparatus is achieved according to the invention. Moreover, the apparatus is particularly suitable for easy and efficient to manufacture.

Because the vessel 20 containing the tube 66 according to the invention is assembled to the collecting tube 96 of the heat exchanger, preferably the gas cooler 92, with the accumulator chamber 24 present in the vessel 20 and the heat exchanger chamber 28 extending parallel to the collecting tube 96 and over a significant section of the length of the chamber, a good result was achieved in terms of compactness. At the same time, a dryer 34 and optionally also a filter 50 in the accumulator chamber and/or heat exchanger chamber of the vessel may also be advantageously offered since the space for this expedient is sufficient. A filter 50 and dryer 34 may ensure the desired drying and purification (treatment) of transcritical refrigerant, which can be CO₂, for example.

Further, the accumulator chamber 24 assists in the functionality of the apparatus, since it contributes to the fact that only gaseous refrigerant reaches the compressor and guarantees its perfect operation on this account.

Moreover, this is not at variance with the fact that small amounts of oil and liquid refrigerant are supplied to the gaseous refrigerant right before leaving the heat exchanger chamber 28 in the direction toward the compressor via an opening in the longitudinal wall. The refrigerant vapor at this location is in a state so that supply of oil and liquid refrigerant results in further cooling by evaporative cooling. The gaseous state of the refrigerant in the compressor is supported on this account and the refrigerant inlet temperature in the compressor is further reduced. In the already-mentioned prior art, the refrigerant must overcome a more or less significant slope after return of the oil, which entails losses. According to the present invention return occurs directly in the suction line, bypassing the internal heat exchanger, so that more favorable heat transfer is present.

The apparatus according to the present invention is thus not only particularly suitable for manufacture, but may also be characterized by its slim configuration contributing to the fact that an ordinary air conditioning unit and an air conditioning unit with transcritical refrigerant, for example CO₂, can be accommodated in essentially the same space. This is a significant advantage for automobile manufacturers, for example, as it permits them to use the same spatial concepts within a series of automobiles for different types of air conditioner. For example, in view of different world-wide environmental regulations, automobiles for one market may be equipped with ordinary air conditioners and automobiles for another market equipped with CO₂ air conditioners, and the present invention enables the basic designs of each such automobile be efficiently consistent notwithstanding the inclusion of different air conditioners.

Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained. 

1. An apparatus for treating refrigerant which passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature circulating in a transcritical air conditioning loop, comprising: a heat exchanger in said loop, said heat exchanger having a collecting tube; a longitudinal vessel connected to said heat exchanger collecting tube and defining a heat exchanger chamber and an accumulator chamber, wherein both of said chambers extend parallel over at least a significant portion of the length of said vessel; and a flat multi-chamber tube extending through said heat exchanger chamber of said vessel, wherein refrigerant on one side flows through said tube and refrigerant on the other side flows through said vessel.
 2. The apparatus of claim 1, further comprising an introduction tube for the low pressure side in the accumulator chamber.
 3. The apparatus of claim 2, further comprising a dryer associated with the introduction tube.
 4. The apparatus of claim 1, further comprising at least one longitudinal wall in said vessel, wherein one end includes at least one inflow opening for the low pressure side from the vessel accumulator chamber into the vessel heat exchanger chamber.
 5. The apparatus of claim 4, further comprising at least one opening on the other end of longitudinal wall for oil contained in the refrigerant.
 6. The apparatus of claim 4, wherein said longitudinal wall is spaced from the center plane of said vessel whereby the accumulator chamber is larger than the heat exchanger chamber.
 7. The apparatus of claim 1, wherein the heat exchanger chamber extends over a partial radius of the vessel interior.
 8. The apparatus of claim 1, wherein the vessel and the flat multi-chamber tube are extruded.
 9. The apparatus of claim 8, wherein the multi-chamber tube extends substantially undeformed through the heat exchanger chamber of the vessel and further comprising heat conducting ribs in the remaining cross-section of the heat exchanger chamber over a majority of the length of the heat exchanger chamber.
 10. The apparatus of claim 1, wherein the vessel is an extruded tube having ends closed by a cover.
 11. The apparatus of claim 10, wherein said extruded tube includes a longitudinal wall separating said heat exchanger chamber from said accumulator chamber.
 12. The apparatus of claim 10, further comprising an insulation plate in the tube.
 13. The apparatus of claim 12, further comprising grooves molded on opposite sides of the tube wall, wherein said insulation plate is inserted in said grooves.
 14. The apparatus of claim 1, further comprising an insulation plate adjacent said longitudinal wall.
 15. The apparatus of claim 1, further comprising shielding between the vessel and the cooling air stream flowing through the heat exchanger.
 16. The apparatus of claim 15, wherein the heat exchanger is a gas cooler.
 17. The apparatus of claim 1, wherein the collecting tube of the heat exchanger and the vessel are assembled compactly together.
 18. The apparatus of claim 1, further comprising an air baffle, wherein the vessel is behind said air baffle in the air flow direction.
 19. The apparatus of claim 1, further comprising insulation at least partially on the outside of said vessel.
 20. The apparatus of claim 1, further comprising one or more refrigerant treating filters in the vessel.
 21. An apparatus for treating refrigerant which passes through a high pressure side and a low pressure side in which the refrigerant has a different temperature circulating in a transcritical air conditioning loop, comprising: a slim, hollow longitudinal vessel with at least one longitudinal wall and defining a heat exchanger chamber and an accumulator chamber, wherein both of said chambers extend parallel over at least a significant portion of the length of said vessel and said vessel including at least one longitudinal wall having an opening allowing the refrigerant to flow through the chambers; and a flat multi-chamber tube extending through said heat exchanger chamber of said vessel, wherein refrigerant on one side flows through said tube and refrigerant on the other side flows through said vessel to exchange heat between refrigerant in said sides.
 22. The apparatus of claim 21, wherein said flat multi-chamber tube extends lengthwise through the heat exchanger chamber with heat conducting ribs.
 23. The apparatus of claim 22, wherein the multi-chamber tube and the heat conducting ribs are extruded.
 24. The apparatus of claim 21, wherein the inserted longitudinal wall has a lower heat transfer value than the walls of said vessel.
 25. The apparatus of claim 24, wherein the inserted longitudinal wall consists of plastic.
 26. The apparatus of claim 21, further comprising heat conducting ribs in the remaining cross-section of the heat exchanger chamber outside of said multi-chamber tube.
 27. The apparatus of claim 21, wherein said longitudinal wall is spaced from the center plane of said vessel.
 28. The apparatus of claim 21, further comprising a dryer in the accumulator chamber and a filter in said vessel.
 29. The apparatus of claim 21, wherein said vessel has a length (L) and a diameter (D), and the ratio of length (L) to diameter (D) is ≧3:1. 